Spectrophotometers are commonly used to make photometric comparisons of spectral characteristics of various samples. Samples could include but are not limited to illumination sources (measuring emission), filters (measuring transmission/absorption) and test patches (measuring reflectance). Typically, spectrophotometers measure a number of wavelength regions in order to quantify the spectral characteristics of a sample. For example, a scanning spectrophotometer may perform a sweep of wavelengths ranging from 570 nm to 610 nm when quantifying the spectral transmission of an interference filter having a central wavelength of 589.3 nm.
Conventional spectrophotometers fail to provide detailed information regarding a large area or linear distance. In other words, conventional spectrophotometers effectively provide an average value, e.g., reflectance at a given wavelength, over the entire measured area or field of view. Thus, in order to determine reflectance values for discrete regions over a larger area, multiple measurements must be taken at different fields of view. Conventional spectrophotometers are not practical options for both spectrally and spatially calibrating a system.
Alternatively, complementary metal-oxide semiconductor (CMOS) or charge-coupled device (CCD) optical detection arrays provide detailed spatial information, but limited spectral information. A monochromatic array integrates the spectral response across all wavelengths, while an array with separate red, green and blue detection, as achieved by filters, provides three pieces of spectral information but at the cost of tripling the number of detection elements.
The present disclosure addresses systems and methods for further improving illumination and detection systems for spectral and spatial calibration of a variety of devices, e.g., a spectrophotometer, a printer, etc.